CAMPCS/3 is designed to follow patients with persistent asthma from the Childhood Asthma Management Program (CAMP) trial for 4 additional years (through ages 21-29) to determine clinical and genetic risk factors for patterns of lung function decline indicative of chronic airflow obstruction in later adulthood. No other study of childhood asthma has the size, detailed phenotyping, and longitudinal follow-up needed to determine these risk factors. CAMP recruited 1041 persistent asthmatics to determine the effect of regular inhaled corticosteroid (ICS) on lung-growth. We are currently following 869 (83% of the original cohort) to determine predictors of attained maximal lung growth in early adulthood for persistent asthmatics. We have identified patterns of reduced growth arid evolving airway obstruction. Analysis of CAMP participants, aged 23 years or older, indicate that 28% did not reach normal maximal level of FEV1 even when measured after bronchodilation. We have also observed that 20% have already started to decline, with the mean age of decline 19.4 years. These abnormalities may be due to persistent inflammation suggestive of early chronic obstructive pulmonary disease. We propose 3 specific aims: 1) Define, using a range of normal comparison populations, susceptible subgroups of patients with persistent childhood asthma who are at risk for patterns of reduced attained maximal lung function and of subsequent decline of lung function, 2) Identify genetic correlates of maximal attained lung function and early lung function decline (genetic analyses will be done by Dr. Weiss and the Center for Genetics and Genomics at Harvard, without cost to this application) relating existing genetic data on more than 700 trios of parents and CAMP patients to the detailed phenotypic data collected during all phases of CAMP, and 3) Determine effects into early adulthood of 4-6 years of prior continuous treatment with inhaled anti-inflammatory medications. Data collection procedures for spirometry and other procedures will be identical to those used in previous phases of the CAMP study. Annual pre- and post-bronchodilator spirometry will allow accurate measurement of lung function. CAMP is the largest, most completely characterized cohort of children with asthma. Follow-up of this cohort in CAMPCS/3 will provide valuable information about the natural history of this important childhood lung disease, which can be used to identify patients with asthma who are at risk of chronic airflow obstruction later in adult life. (End of Abstract.)